Author

Abstract

Purpose of the work is to discuss some theoretical aspects of the diffusion of hydrogen atoms in the crystal lattice of BCC metals at low temperatures using the methods of statistical thermodynamics. The values of the statistical model calculations of H diffusion coefficients in α-Fe, V, Ta, Nb, K are in good agreement with the experimental data. The statistical model can also explain deviations from the Arrhenius equation at temperatures 300-100 K in α-Fe, V, Nb and K. It was suggested that thermally activated fast tunnelling transition of hydrogen atoms through the potential barrier at a temperature below 300 K provides an almost free movement of H atoms in the α-Fe and V lattice at these temperatures. The results show that quantum-statistical effects play a decisive role in the H diffusion in BCC metals at low temperatures. Using the statistical model allows for the prediction of the diffusion coefficient for H in BCC metals at low temperatures, where it’s necessary to consider quantum effects.

Keywords

Hydrogen diffusion; BCC metals; Statistical model; Pre-exponential factor; Low temperature; Quantum-statistical effects